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When to Plant Spinach in Oliver County, ND

Oliver County, North Dakota Zone 4a May

What to do in May

Each item below is timed to Oliver County, North Dakota's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 14
Avg. first frost September 26
Soil temp (4") 54°F
Watering High
Pest pressure Low
Daylight 14.9 hrs
  1. Transplant spinach outside

    Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.

  2. Seed spinach outdoors

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

To set up a strong June, finish these tasks
  • Starting indoors: spinach
  • First harvests: spinach

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Spinach is a nutrient-packed cool-season green that grows quickly in spring and fall. It is rich in iron, vitamins, and antioxidants and excellent raw or cooked.

Oliver County, North Dakota is in USDA Zone 4a. The average last spring frost is May 14 and the first fall frost is September 26, giving you a growing season of approximately 135 days.

At an elevation of 721 feet, Oliver County receives approximately 21.1 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Spinach to ensure they mature before fall.

Oliver County, ND (Zone 4a) Short season
135 days
Last Spring Frost May 14
135 growing days
First Fall Frost September 26

Oliver County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (34 days to spare)
Start indoors: Mar 29 Transplant: May 10 🍅 Harvest: Jun 14 – Aug 16
Recommended (50%) ✓ Fits season (37 days to spare)
Start indoors: Apr 2 Transplant: May 14 🍅 Harvest: Jun 18 – Aug 20
Safe Start (90%) ✓ Fits season (34 days to spare)
Start indoors: Apr 17 Transplant: May 29 🍅 Harvest: Jul 3 – Sep 4

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Soil Compatibility in Oliver County

How your county's soil matches Spinach's growing requirements.

Soil pH

Your soil pH (6.5–7.4) is within Spinach's preferred range (6.5–7.5).

Soil Texture

The loam soil in Oliver County is excellent for Spinach — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.0%) — Spinach will thrive.

How to Plant Spinach

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Spinach

4
successive plantings in your 135-day season

Sow every 4 weeks. Last sowing by Aug 07 to harvest before frost.

For a dedicated fall crop, sow by Jul 04.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.7″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 63 gal / 100 sq ft
Drought risk

Water stress score is 10/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Spinach

Spinach needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Spinach Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 2.3" 0" ❄️ Dormant
May 3" 2.4" 0.6" 💧 Light watering
Jun 3" 1.7" 1.3" 💧 Light watering
Jul 3" 1.9" 1.1" 💧 Light watering
Aug 3" 2.5" 0.5" 💧 Light watering
Sep 3" 1.7" 1.3" 💧 Light watering
Oct 1.7" 0" ❄️ Dormant
Nov 1.3" 0" ❄️ Dormant
Dec 1.4" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Oliver County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Spinach Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Spinach needs ~425 GDD — county provides 1,350 GDD Excellent fit

Spinach Planting Timeline — Oliver County, ND

Spinach Planting Calendar

Activity When Date Range
Start Indoors April 2 Apr 2 – Apr 16
Transplant Outdoors May 14 May 14 – May 28
Direct Sow May 7 May 7 – May 28
Harvest June 18 Jun 18 – Aug 20
Fall Sowing July 4 Jul 4 – Jul 18

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Transplant Outdoors Direct Sow
June Harvest
July Fall Sowing Harvest
August Harvest
September
October
November
December

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · Only during dry spells

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6.5–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 4a

📆 Growing Season

135 days in Oliver County

Growing Tips for Spinach in Oliver County

Direct sow Spinach outdoors after May 14 in Oliver County when soil has warmed and frost danger has passed.

Your generous 135.0-day season in Oliver County allows multiple plantings of Spinach. Sow every 17.0 days for continuous harvest.

General growing tips

Direct sow as soon as soil can be worked in spring. Plant in partial shade for summer crops to delay bolting. Succession plant every 2 weeks for continuous harvest.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Spinach Seeds
Life Cycle Annual
Pollination Wind Pollinated
How to Collect Let plants bolt. Harvest seed stalks when seeds turn tan.
Storage Store airtight; viable 5 years at 35°F, under 45% humidity.

Wind pollinated — isolate 1/2 mile for purity. Easy to let bolt in heat.

Frequently Asked Questions

When should I plant Spinach in Oliver County, ND?

Oliver County is in Zone 4a with an average last frost of May 14. Plan your Spinach planting based on this frost date — see the calendar above for exact timing.

What planting zone is Oliver County, ND?

Oliver County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 14 and first fall frost is September 26.

🌱

Your Oliver County Garden Planner — Free

A 24-page printable planner built for Oliver County (Zone 4a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Oliver County, ND. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.